The invention relates to a method and to a device for producing tapering pipe sections on cylindrical pipes for ground screw foundations. Methods and devices for producing tapering, and more particularly conical sections on cylindrical, and notably metallic, pipes for the production of screw-in foundations used to mount components in the ground are known. The conical sections can be produced in a variety of ways, for example by welding together prefabricated shaped parts, or by hammering preferably seamless cylindrical pipes (see EP 1 105 597 B1). It is also possible to produce them by rolling preferably seamless pipes. The designs of the devices used for this purpose can thus vary accordingly.
However, the aforementioned methods are very complex. Production starting from prefabricated shaped parts, for example, requires a variety of steps (producing the shaped parts, for example by cutting, then bending and welding of the seams, and the like). Production processes based on hammering or rolling cylindrical pipes are not problematic as such, but are very complex in terms of the equipment that is required for the hammering or rolling device. The conventional hammering is associated with high wear and corresponding noise.
The objects are therefore to provide a method, by means of which such tapering sections can be produced on cylindrical pipes, or tapering sections can be produced from cylindrical pipes, for ground screw foundations in a simple and cost-effective manner, and to provide a device for carrying out such a method, which can be produced with reasonable complexity and which also allows for production of the ground screw foundations, which are economical and free of defects, requiring low personnel overhead. Tapering sections shall be considered to include all sections in which the cross-sectional shape or the diameter decreases. In pipes, a tapering section shall be considered to be in particular a section which is rotationally symmetrical relative to the longitudinal direction of the pipe, such as a conical section for example, which is to say a taper or a (truncated) cone, or a section having a curved, and more particularly a convex or concave, surface in the longitudinal direction of the pipe. Non-rotationally symmetrical sections, such as (truncated) cones having an elliptic base area or polygonal pyramids, and more particularly rectangular pyramids, are also tapering sections within the meaning of the invention.